
92-11Data Acquisition Systems
92.7.3 Simultaneous Sampling
For applications where the time relationship between the input signals is important, such as phase analysis
of ac si
gnals,
si
multaneous
sa
mpling
mu
st
be used. DA
Q
bo
ards
ca
pable
of si
multaneous
sa
mpling
ty
pi-
cally
use in
dependent
in
strumentation
am
pliers
an
d
S/
H
ci
rcuitry
fo
r
ea
ch
in
put
ch
annel,
al
ong
wi
th
an
an
alog
MU
X,
wh
ich
ro
utes
th
e
in
put
si
gnals
to th
e
ADC fo
r
co
nversion
(a
s
sh
own
in Fi
gure
92.10
)
.
To de
monstrate
th
e
ne
ed
fo
r
a sim
ultaneous-sampling
DA
Q
bo
ard,
co
nsider
a sy
stem
co
nsisting
of
fo
ur
50 kH
z
in
put
sig
nals
sa
mpled
at 20
0
kS
/s
. If th
e
DA
Q
bo
ard
us
es
co
ntinuous
sc
anni ...